Just melted down my fist WW today and made ignots. I pulled some Zinc out of the pot after I got the hang of it. My first few pots may have been to hot and there is a possiblity I may have melted the Zinc down too.

What happens if I did get some Zinc in with the WW? What problems might I have, or what should I look for when casting bullets?

Just a little bit of zinc will ruin your mix. You'll get edges that aren't sharp, you'll get what look like pits or holes, you'll get a frosted look just in one area, not the entire bullet, plus other abnormalities. They say if you turn your pot down to the level where you alloy melt that you can keep skimming the zinc out with the dross that accumulates on the top of the melt. Don't mix anymore known good alloy in with what you thing is ruined. Zinc melts at a much higher temperature then cast alloys. One way to tell a zinc wheel weight is to drop in on a concrete floor. It will have a ring or hard metal sound, rather then a thud like lead or cast alloy. Also it is very very hard compared to lead or cast alloys. To give you an idea of things made from zinc: old carburaters that weren't aluminum, old car ornaments like they use to put on the middle of the hood, used in your ignition switch, the wind cranks, door handles, and some old miniature toy cars..plus a whole host of other stuff like cheap 25 acp and 380 acp pistols like from Lorcin or Davis.

Joe

The bullets will likely be unbalanced, as the light zinc crystallizes while the lead is still liquid. The sludge will float to the top of the cavity, which likely won't be quite level.

As said before, it will be VERY difficult to get the bullets to fill out. Another problem I have had when I ruined a pot with zinc is that the bottom pour spout will restrict and plug up fairly easily. If you have these problems you cannot "dilute" the zinc by putting in more lead. I have tried and it does not work. You are wasting good lead trying to save bad lead.

You CAN, however, remove zinc from lead by melting it, keeping it just above the melting point, letting it sit undisturbed till the crystals of zinc (which melts at a higher temperature) float to the top and skim them off. This is how commercial lead is freed of zinc.

Hiya
Caught this thread and a question came to mind..

IF.. a mix has some tin in it, and you let the mix stand melted for a while, the tin will also float up to the surface and you would skim the tin out as well as any zinc, correct?

So if you flux the mix at a lower temp first, to keep the tin in the mix, will the zinc still float out?

I am thinking that maybe I mistook what was floating to the top when I melted the last batch of wheelweights for tin, and it was actually zinc.. Oops.

Thanks

If you meet the melting point of the lead, I would think that any lighter metal would float to the top. So that would have to include the tin, unfortunately. At least you might save the lead which would be the majority alloy.

No, tin is completely liquefied and mixed with the lead at any temperature where the lead is liquid. You cannot remove it by skimming. That's an old caster's myth. It does oxidize faster than lead, and skimming off oxidized dross can eventually lower tin levels.

Well almost the same difference John. They say to let you zinc contaminated melt set for long periods, so some of that tin is going to oxidize out in the dross you'll be skimming.

quote:

Originally posted by Ricochet:
No, tin is completely liquefied and mixed with the lead at any temperature where the lead is liquid. You cannot remove it by skimming. That's an old caster's myth. It does oxidize faster than lead, and skimming off oxidized dross can eventually lower tin levels.

Hmmm... So why do we flux then? Is it a homogenization step?

Molten Zinc isn't Miscible in molten lead, it WILL float to the top.

Lead "contaminated" with Zinc?
In point of fact any lead you are ever likely to see has had Zinc intentionally mixed into it...

Why you ask? because most (if not all) lead ores contain some quantity of Silver (considered a valuble contaminant) and the Zinc is used to seperate Silver from the lead, IIRC Silver is around 3000times more soluble in molten zinc than in Molten lead.

Look up something called the "Parke's Process"
the same process also removes the traces of
gold frequently found in lead ores from some sources.

And no, in a melt containing Lead, Tin and Zinc
the tin will be in solution and during your "long sitting"
there will be a layer of Zinc "dross" protecting the tin
from the action of air.

If you are worried about tin loss leave a layer of molten boric acid on top of the melt to protect it from air.

AD

quote:

Originally posted by RDub:

quote:

Originally posted by Ricochet:
No, tin is completely liquefied and mixed with the lead at any temperature where the lead is liquid. ....

Hmmm... So why do we flux then? Is it a homogenization step?

Why? First, flux comes from the latin word meaning 'to clean'.

Most fluxes produce something that keeps the oxygen from getting near the surface - which prevents oxidation of the metals in the alloy which are commonly skimmed off as dross.

If I remember right, the tin oxidizes very easily - more so than lead.

Tin does oxidize much more easily than lead but the surface area interface with the air is relatively very small, you think of area but realize that that thin layer is only a few atoms thick....

Seperating zinc out is EASY and doesn't "ruin" the melt metal OR the pot it's melted in.
It just requires a bit of extra work.

Keep it melted but turn down the temp the Zinc will crystalize and float, skim it. keep repeating.

what keeps zinc partially in solution with some melts
is a metal that will mix with both Zinc and lead, copper.
Copper is the REAL "Boogeyman" of lead casting as it does most of the things that Zinc gets blammed for.

The worst thing copper does is it "steals" tin from the melt, because tin has a great affinity for copper
but so does Zinc...

The presence of tin makes using zinc to remove copper less effective and takes tin with the copper.

The worst batches I've seen for copper contamination have
been recovered (indoor) range lead, particularly if a lot of
copper or brass washed 22LR bullets are included in the mix.

this material requires long repeated tedious processing, but it is far from hopeless and can be made far easier by dealing with the metal in larger quantities.

I do my smelting in a 6quart dutch oven (with a lid) over the burner from a Brinkmann Cajun cooker/smoker.

Hell I keep my skimmed dross in 3lb coffee cans and I later recover the lead from that as well.

I recover that lead by "baking" the can in my coal stove
and draining the lead out for reprocessing

AD

I was having trouble with zinc (a loooong time ago) until I fluxed a couple times and ran the pot a little hotter. My molds were filled completely, all the edges were nice and crisp and when properly sized and lubed shot some exelent groups. Mine tended to frost lightly all over so I turned the pot down just a tad; found the right combo I guess. Now they look like sterling silver and shoot like gold.

Hey Allan please read my post on copper mixing with lead can you help me out?

now that begs the question: why do most of the old British Dangerous Game Muzzleloaders use a significant amount of Zinc in the roundball and elongated bullets? Read Selous' book and note that he says they use zinc to harden the alloy for better penetration. It would be interesting to pour about five pounds of say, 20:1 lead/tin alloy, and then put about 2-3% zinc into the alloy and pour the equivalent amount of that alloy, and see what the diameter difference and Bhn would be. Then, shoot them in a known moa rifle with a good scope.
Volunteers...?

Rich
DRSS
Knowledge not shared is knowledge lost...

Sometimes, metals do not just mix. What happens is one metal will go into solution in another. I would think that is what happens with lead and zinc and that would require enough heat. The same thing would happen with copper. Disolving copper into lead would require enough time with the lead at an appropriate temperature and the copper still solid. (Think of copper soldering iron tips - they dissolve). Too slow a cooling of the solution could cause the higher melting point metal to freeze out and I suppose this could result in an uneven distribution of lead and zinc in the bullet.

Now that you folks have given me the idea, I am going to give it a try. (Copper/lead alloy that is).